1. Field of the Invention
The invention relates to an operator control element for motor vehicles having a fixed base body, a handle which is mounted so as to be capable of rotating about an axis in the base body, display windows which are arranged radially around the axis, and an illumination device for illuminating at least one of the display windows. In addition, the invention relates to a method for determining the rotary position of a rotatable operator control element.
2. Description of the Prior Art
An operator control element of the type described at the beginning is known, for example, from DE 101 27 211. Such operator control elements are used, for example, in operator control units for motor vehicle air-conditioning systems as rotary switches for setting the air distribution or as rotary potentiometers for predefining a temperature value. Display windows which characterize the set state by means of symbols which are provided are arranged around the rotatable handle. So that the symbols can be recognized even when operating the device at night, a means of illuminating the display windows or one of the display windows which represents the set value is necessary. For this purpose, light sources are used in the form of light-emitting diodes and lightguides. The light-emitting diodes which are used to illuminate the symbols are actuated by a microcontroller of the operator control part in order to control the brightness of the display or switch it on/off. When the operator control elements are used in motor vehicles, a high degree of precision in the supplied state is required or it is necessary to perform standardization, for example on potentiometers.